Preparation of an effective light-cured bonding agent for orthodontic application.
OBJECTIVE
The purpose of this study was to prepare a light-cured adhesive applicable for orthodontics by mixing monomers and a polymerized reactive organic composite filler (prepolymerized trimethylolpropane trimethacrylate-filler, TMPT-filler).


METHODS
The monomer component was a mixture of 3.0 wt% 2-hydroxy-3-(2-naphthoxy)propyl methacrylate (HNPM) in triethylene glycol dimethacrylate. This was applied to extracted bovine tooth enamel after acid etching with 65 wt% phosphoric acid for 30 s. After 24 h in 37 degrees C water, the tensile bond strength was measured, and the data were analyzed with Duncan's new multiple range test (p < 0.01 or 0.05).


RESULTS
The tensile bonding strength to enamel etched with 65 wt% phosphoric acid was 13.1 +/- 0.5 MPa, and the thermal stability of the bond was excellent. SEM examination of the cross-sectioned specimens modified with HCl demineralization showed that when the diffusion time prior to light irradiation was only 1 min, a well-developed resin honeycomb-like structure was created in the enamel surface in the formulation containing HNPM.


CONCLUSIONS
Monomer impregnation beyond the etched enamel surface was important for resin-enamel bonding, increasing bonding strength and thermal stability. HNPM was effective in enhancing monomer diffusion and impregnation of the etched enamel surface.
Gunadi
G
G
Second Department of Orthodontics, Faculty of Dentistry, Tokyo Medical and Dental University, Japan.
Nakabayashi
N
N
D000179:Acrylates / Q000737:chemistry; D000818:Animals; D002417:Cattle; D001840:Dental Bonding; D003743:Dental Enamel / Q000737:chemistry / Q000648:ultrastructure; D004058:Diffusion; D008027:Light; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry*; D008768:Methylmethacrylates / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D009967:Orthodontic Appliances; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D019904:Polymethyl Methacrylate; D019279:Resin Cements / Q000737:chemistry*; D013718:Tensile Strength; D013729:Terpenes / Q000737:chemistry
D000179:Acrylates; D008689:Methacrylates; D008768:Methylmethacrylates; D011109:Polymethacrylic Acids; D019279:Resin Cements; D013729:Terpenes; C020946:triethylene glycol dimethacrylate; C035600:dimethylaminoethyl methacrylate-methylmethacrylate copolymer; D011092:Polyethylene Glycols; C048339:camphoroquinone; C027993:trimethylolpropane triacrylate; C031171:2-hydroxy-3-beta-naphthoxypropyl methacrylate; D019904:Polymethyl Methacrylate